Special milling machine for slewing post-welding machining of tower crane and machining method

The invention discloses a special milling machine for slewing post-welding machining of a tower crane and a machining method. The special milling machine comprises a supporting base, a sliding rail, a power head and a slewing fixing device; a sliding table is arranged on the sliding rail; the lower end of the slewing fixing device is arranged on the sliding rail through the sliding table; the slewing fixing device is screwed to the upper end of the sliding rail; the power head is welded and fixed to the position,located at the upper end of the slewing fixing device, on the upper side of the supporting base; and a facing cutter is screwed to the lower end of the power head. According to the special milling machine, in a process that a slewing bearing rotates and drives the workpiece to slew, the a machining face of a workpiece is milled using the facing cutter, which implements that a feeding path is round, and can fit with the machining face of the workpiece, so that the workpiece can be machined rapidly and